Flotation process with 2-cyanovinyl alkylxanthates



ficiation of ores by froth flotation.

United States Patent 4 Claims. (Cl. 209-166) This application is a division of copending application Serial Number 243,615 and now Patent Number 3,226,- 417, filed December 10, 1962.

This invention relates to the provision of a new class of compounds. More particularly, it relates to a class of 2-cyanovinyl alkylxanthates which can be prepared by the novel reaction of a metal salt of an O-xanthic ester with ,B-haloacrylonitrile.

It is an object of this invention to provide, as a new class of compounds, S-(Z-cyanovinyl) O-xanthic acid esters by a new reaction in which a metal salt of an O- Xanthic ester is cyanovinylated with a fl-haloacrylonitrile. It is a further object of this invention to provide a class of compounds which are useful as promoters in the bene- It is still a further object of this invention to provide a class of compounds which have inseCticidaLfungiCidal and bacteriocidal properties.

Other objects will be apparent from the following detailed description in conjunction with examples showing preferred embodiments of the present invention.

The Z-cyanovinyl alkylxanthates of the present invention may be represented by the following general Formula I:

R'O-C'S-CH=OHCN' I wherein R is an alkyl or aralkyl group. Alkyl groups may contain up to twelve carbons and may be substituted with one or more (e.g., up to about three) electronegative groups such as halogen (e.g., chloro, bromo, and fiuoro), nitro, cyano, lower alkoxy or amino groups. Aralkyl groups may be monocyclic (lower alkyl) or bicyclic (lower alkyl) groups having up to about three halo (e.g., fluoro, chloro or bromo), lower alkyl, cyano, lower alkoxy, amino or nitro radicals.

Compounds of Formula I are prepared by the reaction of a 'B-haloacrylonitrile with a metal salt of an O-Xanthic acid ester, represented by the following Equation (A):

ROCSM XCH CHCN ROFSCH=CHCN MX wherein M is an alkali metal (e.g., potassium or sodium), R is as defined above and X is chloro or bromo. The reaction may be advantageously conducted by contacting the reactants at ambient temperatures or lower (e.g., about 03'0 C.). Proportions are not critical and equimolar amounts or an excess of either reactant, may be used. The reaction can be carried out in aqueous medium, in which case the product separates as an oil and the alkali metal halide stays in solution. Or else an inert organic solvent such as acetone, chloroform or ether, may be used, in which case the product remains in solution and the salt separates as a precipitate. If desired, the product may be purified by conventional methods, employing solvents for extraction from aqueous reaction media followed by distillation.

Among the alkali metal xanthates which can be named as suitable for reaction with either B-chloroacrylonitrile 3,301,400 Patented Jan. 31, 1967 or B-bromoacrylonitn'le are the sodium and potassium salts of the following O-xanthates:

(1) Alkylxanthates such as methylxanthate, ethylxanthate, isopropylxanthate, n-butyl and secondary butylxanthate, amylxanthate, hexylxanthate, octylxanthate, dodecylxanthate, 2 chloroethylxanthate, nitromethylxanthate, Z-methoxyethylxanthate, 2-n-propylxanthate, 2- cyanoethylxanthate, and the like; and

(2) Aralkylxanthates such as benzylxanthate, phenethylxanthate, a-naphthylmethylxanthate, 3,4-dichlorobenzylxanthate, p-chlorophenethylxanthate, xylylmethylxanthate, p-cyanobenzylxanthate, anisylmethylxanthate, p-nitrobenzylxanthate, p-aminobenzylxanthate, and the like.

Compounds of Formula I have useful biocidal properties, being active in inhibiting the growth of such fungi as Aspergillus flavus, Chaetomium globosum, Fusarium moniliforme, Penicillium citrinum and T richoderme viride; and such bacteria as Bacillus mycoides. Furthermore, they are active insecticides, giving 100% kill against aphids at concentrations below about 1%.

Additionally, such compounds have valuable froth-flotation promoting properties, and can be used in conventional flotation operations for the recovery of copper, lead, zinc and iron from sulfide ores containing these metals.

The following examples are presented to further illustrate the present invention.

EXAMPLE 1 Z-cyanovinyl ethylxanthate To 16.0 g. of potassium ethylxanthate in 50ml. of water, there was added 9.7 g. of cis-fi-chloroacrylonitrile over a 15 minute period. A slight exotherm was noted. The mixture, after having been stirred for 24 hours at room temperature, consisted of an aqueous layer, an oil, and a suspended solid. The latter, weighing 1.2 g., melted at 140l42 C. and was identified as cis-;8,fi'-thiodiacrylonitrile, a by-product. The oil was extracted with chloroform, washed with water, treated with activated carbon, and filtered. The solvent was then removed at high vacuum leaving 14.0 g. (81% yield) of a brown oil, 11 1.5868, identified as cis-Z-cyanovinyl ethylxanthate.

EXAMPLE 2 Z-cyanovinyl isopropylxanthate The procedure of Example 1 was repeated, except that the reaction was carried for 2 hours at 10 C. followed by 1 hour at room temperature. The reactants were 15.8 g. of sodium isopropylxanthate and 8.8 g. of cis-,8-chloroacrylonitrile. In addition to a small quantity of fi,/3'- thiodiacrylonitrile, cis-Z-cyanovinyl isopropylxanthate was obtained as a brown oil weighing 13.5 g. (72% yield), 11 1.5722.

EXAMPLE "3 Z-cyanovinyl amy lxanthate .To 20.2 g. of potassium amylxanthate in ml. of acetone there was added over a 15 minute period a solution of 9.6 g. of cis-[i-chloroacrylonitrile dissolved in 50 ml. of acetone. The mixture was stirred and kept below 15 C., both during the addition and for 3 hours thereafter. The slurry was filtered to remove potassium chloride. The filtrate was then treated with activated carbon and filtered. Upon evaporation of the solvent under a high vacuum, there remained an oil with -a few suspended crystals of fl, 8-thiodiacrylonitrile which were removed by filtration. The product, cis-Z-cyanovinyl amylxanthate, was a brown oil, 11 1.5444, weighing 13.5 g. (63% yield).

3 EXAMPLE 4 Z-cyanovinyl isopropylxanthate The procedure of Example 3 was repeated except that 15.8 g. of sodium isopropylxanthate was used and that the B-chloro-acrylonitrile was the trans isomer. The product was obtained as a light yellow oil, n =1.5 85 8. The yield was 14.7 g. (79% The infrared spectrum showed bands at 2220 (nitrile), 1577 (double bond), 1037, 1090 and 1257 cm. (xanthate ester). In addition, it showed bands at 850 and 988 cm. which are similar to those of other known trans-substituted acrylonitriles. The product is, therefore, trans-cyanovinyl isopropylxanthate. Less than 2%, if any, cis isomer was present.

EXAMPLE 5 Z-cyanovinyl ethylxanthate The procedure of Example 4 was repeated, except that 16.0 g. of potassium ethylxanthate was used. The product was obtained as a yellow liquid n =l.5993; in a 74% yield. There was also collected 1.6 g. of trans- /3,/3'-thiodiacrylonitrile, melting point 1289 C., a byproduct. The product exhibited bands in the infrared at 847, 930, 997 cm. (trans), 1040, 1240 cm. (xanthate ester), 1575 cm. (double bond), 2220 cm. (nitrile). There was no band at 710 cmf where cis-,B-substituted acrylonitriles absorb. It can be seen that the reaction is highly stereo-specific, i.e., cis/3-chloroacrylonitrile gives cis esters, while trans-fi-chloroacrylonitrile gives trans esters. Likewise, a racemic mixture gives a racemic product.

EXAMPLE 6 Z-cycmovinyl dodecylxanthate The product is obtained by following the procedure of Example 3 except for the substitution of an equimolar amount of potassium dodecylxanthate for the xanthate used therein.

EXAMPLE 7 Z-cyanovinyl nitromethylxanthate The product is obtained by following the procedure of Example 3 except for the substitution of an equimolar amount of nitromethylxanthate for the xanthate used therein.

EXAMPLE 8 2cyan0vinyl cyanoethylxanthate The product is obtained by following the procedure of Example 3 except for the substitution of cyanoethylxanthate for the xanthate used therein.

EXAMPLE 9 '2-cyan0vinyl phenethylxanthate The product is obtained by following the procedure of Example 3 except for the substitution of. an equimolar amount of phenethylxanthate for the xanthate used there- 1 1- EXAMPLE 10 EXAMPLE 1 1 A second copper ore (0.68% Cu) from the Western United States was ground 6 minutes at 60% solids with 1.5 lb. lime/ton (ph=7.8) and 0.05 lb. promoter/ton, conditioned 5 minutes at 22% solids with 0.1 lb. polypropylene glycol per ton as frother, and floated for 4 minutes. Used as promoters wer the product of Example 2 and allyl amylxanthate, a well-known promoter (for comparison). The following results are obtained.

TABLE II i Percent No. Compound Cu In Tailing 1 Allyl amylxanthate 0. 16 2 cis-cyanovinyl isopropylxanthate 0.081

I claim:

1. The process of beneficiating metal sulfide ores which comprises grinding said ores and subjecting the ground ore to froth flotation in the presenc of a compound of the formula:

wherein R is a member selected from the group consisting of alkyl radicals having up to twelve carbon atoms and lower aralkyl radicals of less than three rings.

2. The process of claim 1 wherein R is isopropyl.

3. The process of claim 1 wherein R is sec-butyl.

4. The process of claim 1 wherein the ore is a coppercontaining ore.

References Cited by the Examiner UNITED STATES PATENTS 1,440,962 4/1922 Cadwell 260-455 2,307,769 1/ 1943 Hechenbleikner 260-455 2,696,496 12/1954 Craig 260-455 2,865,941 12/1958 DAmico 260-455 3,150,119 9/1964 Hotfenberg et al. 260-455 X 3. 26.4 2 6 k l s ate-16 x HARRY B. THORNTON, Primary Examiner, R.- H LPER, 4 m"! Emi tin 

1. THE PROCESS OF BENEFICIATING METAL SULFIDE ORES WHICH COMPRISES GRINDING SAID ORES AND SUBJECTING THE GROUND ORE TO FROTH FLOTATION IN THE PRESENCE OF A COMPOUND OF THE FORMULA: 